It is known that vehicle users, particularly of two-wheeled vehicles, wish to be able to leave their helmets without risk of such helmuts being stolen when they park their vehicles.
Helmet anti-theft devices made of a metal cage that remains on the vehicle are known for this purpose. This cage can be secured by a lock and key. However, such a device has the disadvantage of taking up a great deal of space.
Other devices comprise a hook, attached for example to the handlebars, which can pass through an opening in the helmet and then be locked.
These various device require the use of a special key and in addition leave the helmet exposed to the weather.